In recent years, surface-launched acoustic wave sensors, and specifically surface acoustic wave (SAW) sensors, have gained significant recognition as tools for measuring physical and chemical parameters in a wide variety of applications. SAW sensor technology offers the following general advantages: passive device operation (no battery); potential for use as a sensor and an RF transmitter when queried, providing wireless operation; small size, low cost, rugged construction, and ease of production in high volume using standard process equipment. Some of the physical parameters measured using SAW sensors include temperature, pressure, strain, acceleration, and torque. Numerous potential applications have been mentioned in the literature for such sensors, one of which is the measurement of the pressure and/or temperature within tires.
One of the problems with conventional SAW sensors is that there are multiple international and national government regulations governing the use of radio frequencies with regard to interrogating a wireless sensor, such as a SAW sensor. Because regulations are different throughout the world, sensor suppliers are forced to manufacture multiple sensors that perform the same function but differ by the method or frequency in which the sensor is measured in order to accommodate all the applications worldwide. The embodiments disclosed herein address this problem by providing a configuration in which multiple sensing elements are placed on a single sensor so that the same product can be utilized internationally.